Temporal variation in a plant-seed disperser network in subtropical Andean montane forests

PEDRO G. BLENDINGER; MARÍA G. NUÑEZ-MONTELLANO; ROMÁN A. RUGGERA; LEANDRO MACCHI; EDUARDO MARTIN; MARÍA E. ÁLVAREZ; ORIANA OSINAGA ACOSTA; ROCÍO SÁNCHEZ; PATRICIA V. ZELAYA; JOSEFINA HAEDO

Campos do Jordao

Congreso; 25th International Ornithological Congress; 2010

Plant-seed disperser mutualistic networks are strongly structured, however little is known about how this structure changes through time. We studied the temporal variation in structure properties of a mutualistic network of 15 bird and 21 plant species and we evaluated the effects of species abundance and ecological and morphological traits of birds and plants to determine the interaction patterns of the mutualistic partners. Since Sep 2008 we sampled bimonthly the abundance of ornithocorus fruits, abundance of fruit-eating birds and fruit consumption in Yungas forests, Argentina. Global network connectance and richness ratio (bird:plant) were lower than seasonal connectance and richness ratio values, although these last two properties were more similar to global values in autumn when fruit consumption was highly skewed because of a hyperabundant fruit species. Birds and plants showed striking similarities but also differences in the temporal variation of their network properties. The pairwise interaction frequency had the largest effect over the interaction properties of both groups of species. The abundance of mutualistic partners had a larger effect on quantitative than binary network properties. The species identity and ecological and morphological traits explained a small fraction of the temporal variation in the interaction properties, and were more important for birds than plants. These findings showed that some attributes of plant-seed disperser network structure and network properties of the mutualistic partners vary through time, suggesting that temporal dynamics in the relative importance of the mechanisms contribute to network structure.